The present invention relates to a technique for facilitating the alignment or positioning of an antenna adaptable for receiving transmitted signals.
In an analog broadcasting system (such as that associated with an NTSC TV system or the like), analog television signals may be transmitted and received by a number of television receivers with the use of respective antennas. Each of such antennas may be aligned by moving or rotating the same until an acceptable picture is displayed on the respective television receiver. In such system, a picture signal may be received and the corresponding picture displayed on a respective display screen of the television receiver in real time or substantially real time. As a result, since a picture signal may be received and the corresponding picture displayed on the screen of the television receiver in real time, changes in the displayed picture may be viewed in real time as the respective reception antenna is moved or rotated. Such ability to display pictures and changes thereto in real time enables the optimum or acceptable orientation or alignment of the antenna to be easily found.
In a digital television (DTV) broadcasting system, broadcasted DTV signals may be transmitted from a DTV transmitter directly or by way of a satellite or other type of relaying device(s) for reception by a number of television receivers with the use of antennas. Such broadcasted DTV signals may enable clearer pictures and sound to be produced by the television receivers as compared to those obtained from broadcasted analog television signals (such as those associated with the NTSC TV system). However, in a DTV broadcasting system, it may be difficult to align an antenna so as to properly receive the broadcasted television signals. That is, in a DTV broadcasting system, a picture may be received, processed and displayed wherein such processing could take several seconds or longer. As a result, a delay of several seconds or longer may occur from the time in which the picture signal is received until the corresponding picture is displayed so that a picture signal may not be received and the corresponding picture displayed on the television receiver in real time. Such inability to receive and display in real time may inhibit the finding of the optimum or acceptable orientation or alignment of the antenna.
Further, DTV transmitters may be located on different towers and/or at different locations on the same tower. As a result, a receiving antenna coupled to a user's television receiver may need to be positioned so as to properly receive signals transmitted from such different towers and/or locations. Additionally, even if the DTV transmitters or the antennas thereof are at the same locations but are located at different heights and/or are transmitting at different frequencies, the multipaths may be different thereby necessitating different respective orientations of a user's antenna so as to obtain optimal reception.
The above-mentioned processing delay may be due to the processing performed by the receiver, such as the digital receiver 8 illustrated in FIG. 1. Such digital receiver 8 may include a tuner 10, a demodulator 12, a demultiplexer 14, an audio decoder 16, a video decoder 18, and a microprocessor 20 which may be arranged as shown in FIG. 1. In the receiver 10, a broadcasted DTV signal may be received by the tuner 10 by way of antenna 22. The tuner 10 may include a phase-locked-loop (PLL) circuit. An output from the tuner 10 may be supplied to the demodulator 12 so as to be demodulated. A demodulated signal from the demodulator 12 may be supplied to the demultiplexer 14 so as to be demultiplexed into audio and video signals which may be respectively supplied to audio decoder 16 and video decoder 18. The tuner 10, demodulator 12, demultiplexer 14, and decoders 16 and 18 may be controlled by the microprocessor 20. The processing performed from the tuner 10 to the decoders 16 and 18 may cause the above-mentioned delay of several seconds or longer.
Thus, due to the afore-mentioned processing delay, it may be difficult for a user to adjust the orientation or positioning of an antenna for use in a DTV broadcasting system by using the TV picture as an indicator.